Pulse shaping for data transmission in an orthogonal frequency division multiplexed system
AssigneeTelefonaktiebolaget LM Ericsson
InventorsPerols Leif Mikael Gudmundson, Lars Gustav Brismark, Per-Olof Anderson
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Abstract
A method and system for data transmission in a orthogonal frequency division multiplexed (OFDM) system is provided. In the invention each of a plurality of data symbols C.sub.k, having a symbol period T, are modulated onto one of a plurality of subcarriers comprising a first data signal. The first data signal is then multiplied by a pulseshaping function over the period T to generate a second data signal. The second data signal is then transmitted on a system carrier over a communications channel of the OFDM system.
Claims28
In a telecommunications system in which communications between a transmitter and a receiver are carried on a plurality of subcarriers over a communications channel on a system carrier, a method of transmitting data over said communications channel, said method comprising the steps of:
- modulating each of a plurality of data symbols onto one of a plurality of subcarriers to generate a plurality of modulated subcarriers, said modulated subcarriers comprising a first data signal;
- multiplying said first data signal by a pulseshaping waveform to generate a second data signal, said pulseshaping waveform comprising a function having at least one first and second amplitude wherein said first amplitude is greater than said second amplitude;
- and
- transmitting said second data signal on said system carrier.
An apparatus for transmitting data in a telecommunications system in which communications between a transmitter and a receiver are carried on a plurality of subcarriers over a communications channel on a system carrier, said apparatus comprising:
- inverse fast fourier transform (IFFT) circuitry for performing an IFFT on a plurality of data symbols and generating a first data signal;
- a multiplier for multiplying said first data signal by a pulseshaping function in a time domain to generate a second data signal, the pulse shaping function comprising a raised cosine pulse having a predetermined rolloff factor;
- and
- a transmitter for transmitting said second data signal on said communications channel.
An apparatus for receiving data in a telecommunications system in which communications between a transmitter and a receiver are carried on a plurality of subcarriers over a communications channel on a system carrier having a frequency f.sub.c, said apparatus comprising:
- a receiver for receiving a first data signal transmitted on said communications channel and providing a second data signal b.sub.n comprising N discrete time values;
- combiner circuitry for combining said second data signal b.sub.n to generate a combined signal y.sub.n comprising N discrete time values;
- and
- fast fourier transform (FFT) circuitry for performing an FFT on said combined signal y.sub.n and generating a plurality of data symbols C.sub.k, k=0, . . . , N'-1, each of said time discrete values of y.sub.n being associated in said FFT with a frequency f.sub.k =f.sub.c +.varies.k/T and .varies. is a constant greater than one.
In a telecommunication system in which communication between the transmitter and receiver are carried on a plurality of subcarriers over a communications channel on a system carrier having a frequency f.sub.c, a method of transmitting data over said communications channel, said method comprising the steps of:
- modulating each of a plurality of data symbols C.sub.k, having a symbol period T, onto a subcarrier having a frequency f.sub.k, where k=0, . . . , N'-1, wherein f.sub.k =f.sub.c +.varies.k/T and .varies. is a constant greater than one, to generate a plurality of modulated subcarriers, said modulated subcarriers comprising a first data signal;
- multiplying said first data signal by a pulseshaping waveform to generate a second data signal, said pulse-shaping waveform comprising a function having at least one first and second amplitude, wherein said first amplitude is greater than said second amplitude;
- and
- transmitting said second data signal on said system carrier.
Dependencies are inferred from the claim text.